Fluctuations and instability in key economic variables, including economic growth, productivity, international trade, prices, and government expenditure, can lead to deviations of the real Exchange rate from its equilibrium level. Furthermore, external factors such as multi-rate currency systems and financial sanctions can exacerbate these deviations. These Exchange rate misalignments exert significant impacts on investment, economic growth and development, trade flows, balance of payments equilibrium, optimal resource allocation, and other crucial economic variables and indicators. Given the historical prevalence of Exchange rate fluctuations within the Iranian economy and the profound impact of these deviations on the country's economic performance, this study investigates the determinants of the real Exchange rate and the mechanisms through which deviations arise. Subsequently, it examines the potential impact of Exchange rate policies, specifically Exchange rate unification, on mitigating these deviations from the equilibrium level. To this end, utilizing time series data on key macroeconomic variables spanning the period from 1975 to 2020, an empirical model of real Exchange rate deviation is estimated employing the Vector Autoregression (VAR) method. The empirical findings demonstrate a significant response of Exchange rate deviations to the implementation of Exchange rate policies, particularly through Exchange rate unification or improvements in institutional quality within the specified timeframe. The overall results suggest that an optimal Exchange rate policy, achieved through Exchange rate unification, contributes to dampening real Exchange rate deviations and fostering greater Exchange rate stability.

The effect of Exchange rate change on prices, which is known as Exchange rate pass-through in economic literature, has been one of the important factors of inflationary pressures in Iran's economy. In order to estimate the degree of Exchange rate pass-through, a vector error correction model for Iran's macroeconomics with two long run structural relationships including the long run price relationship and the long run real production relationship. Considering that during the recent decades, Iran's economy has mainly witnessed the multiple Exchange rate system, the estimation of the Exchange rate pass-through based solely on the unofficial Exchange rate and without considering the preferential rates cannot be relied upon. For this reason, the estimated model includes three Exchange rates (the unofficial Exchange rate, and tow preferential Exchange rate (Nima and Mobadele) to Exchange rate pass-through can be estimated separately for each rate. The results indicate that the degree of Exchange rate pass-through for the preferential Exchange rates (Mobadele and Nima) in the long run (six years) is equal to 8/9% and 8/4% and in the case of fixing preferential rates, the degree of Exchange rate pass-through will decrease from 2/46% to 6/30%. The results also indicate that although the fixing of preferential Exchange rates leads to a decrease in the degree of Exchange rate pass-through during the stabilization period, but it will increase in the same proportion during the adjustment period of the preferential Exchange rates.

Understanding the identity of phenomenon and their relation is one of the function of science. the insight of this knowledge can help scientists to predict the future and make the background of changes and decisions.In addition to understanding of phenomenon relationship some other studies try to compare the theories and find the best one on the point of their predictability. In this study we tried to review different paradigm and thoughts and theories of Exchange rate and its behavior and also to compare their ability in forecasting the behavior of Exchange rate, for this reason we postulate four theories of Exchange rate which are: mondell-flemming theory, purchasing power parity thory, asset market theory and monetary with flexible price.Our time framework include "in the sample" and "out of sample" data and our case study in this research is examining the behavior of GBP/USD in foreign Exchange market (FOREX), in the sample data include 01/01/1988 to 01/06/2008 monthly and out of sample data include 01/01/2006 to 01/06/2008.In this research we postulated the theories with in the sample data and after examining the validity of model with macro econometric techniques, then with extracting the four measures RMSE, MAPE, MAE and THEIL INEQUALITY COEFFICIENT we evaluated the ability of forecasting each model based on its theory. Finally the result of the study showed that in the mentioned time framework mondell-flemming model could forecast the behavior of GBP/USD better than other theories.

This paper intends to draw the relation between real Exchange rate variability and the choice of Exchange rate regime. The hypothesis was tested by estimating a simultaneous Limited-Dependent variable model with data from a time series during 1973-1996. The paper examines a number of exogenous determinants of Exchange rate variability and the choice of Exchange rate regime.Our results indicate that: 1) The more opening in Iran's economy, the greater in REER variability, 2) An increase in domestic monetary shocks will result in greater REER variability, 3) REER variability decreases in the fixed Exchange rate regime, 4) As an openness increases, the choice of the floating regime is more suitable, 5) The greater REER variability, the more likely a fixed Exchange rate.

In this study, the effect of Exchange rate fluctuations on abnormal returns of companies listed on the Stock Exchange were studied. In this study, Auto Regressive Distributed Lag model due to its ability to explain this connection was used for short-term and long-term. To evaluate the effect of Exchange rate fluctuations, the banks' legal deposit at the central bank, GDP, inflation, current account and capital account on the stock market according to the designated filters, exporting companies that gained the research conditions, were determined. In this study, the company's export price index was calculated at the end of each quarter and abnormal returns were calculated for the group of companies. After calculating abnormal returns of firms, independent and control variables in the ARDL model imported and the effects of the explanatory variables investigation revealed abnormal returns. The results show that the Exchange rate fluctuations variable has a positive and significant impact on exporting companies are abnormal returns.

According to the theory of macroeconomics, achieving stable equilibrium in economy is possible when Exchange rate regimes are consistent with the financial and monetary policies. Besides, regulating the real rate of Exchange and its relation to a known Exchange rate regime, which corresponds to economic conditions, is very important to create the equilibrium This study tries to forecast an Exchange rate which can guarantee the growth of non-oil exports, by emphasizing on making Exchange rate regime consistent with the Exchange rate on the one hand and making financial and monetary policies harmonious with devaluation of  Rial on the other hand. To this end, we have employed a VAR model to determine an appropriate Exchange rate to forecast the behavior of Exchange rate and other related variables over 1996-2000 (1375-79) period. In this framework, a model is worked out to can simultaneously specify the effects of financial policies, liquidity growth, inflation, and devaluation of Rial on non-oil exports within a five-year period. For this purpose, a model is presented with five endogenous and four exogenous variables. The results show that an increase in inflation cancels out the positive effects of devaluation on non-oil exports. Rial devaluation will boost the growth of non-oil exports if it is accompanied by appropriate financial policies. Therefore, if the control of government expenditures is hinged with the devaluation of Rial, it may lead to a reduction in the growth of liquidity and inflation as well as to the growth of non-oil exports.

The purpose of this study is to find an accurate estimate of the Exchange rate-CPI relationship in Iran over the past three decades. The results of the Granger causality test in the frequency domain demonstrate a strong causation from the Exchange rate to CPI especially in the long run. The results of the wavelet analysis show that in the currency crisis periods, the Exchange rate-CPI correlation rises not only for the long run (low frequencies) but for the short run (high frequencies). According to the results of the state-space model, the Exchange rate pass-through jumps in the currency crisis periods, consistent with the results obtained via the wavelet analysis.

The purpose of this research is to examine the Exchange rate increase, Exchange rate gap, and Exchange rate fluctuations in creating a foreign trade advantage within the framework of the resistance economy system based on modeling Exchange rate fluctuations. We are seeking to answer the question of whether Exchange rate changes affect asset returns within the framework of an asset pricing model based on foreign trade in the resistance economy system? If they do, is this effect positive or negative? Resistance economy is a literature that has been proposed in confronting international sanctions. Currently, the Iranian economy must step on the right foundation and principles so that it can overcome international sanctions and turn the threat of sanctions into an opportunity. Those principles and foundations that the Iranian economy must have have created a literature called resistance economy. Monetary and fiscal policies must be specified in this economic literature and we must always answer the question of what we are looking for in the policies we implement. In order to understand what monetary and fiscal policies should be like and what direction they should follow, we must first have a proper understanding of the Iranian economy and the main problem of the Iranian economy. For example, a policy is implemented with a goal, but then it becomes clear that not only have we not reached the goal, but we have also moved away from it.